1. Field of the Invention
The present invention relates to a lithography technology, and more particularly to a surface position measuring system, an exposure method and a semiconductor device manufacturing method.
2. Description of the Related Art
In fabricating semiconductor devices, the images of mask patterns formed on a photomask are projected onto a resist film by using an exposure apparatus. In fabricating fine semiconductor devices, it is essential to form the projection images of the mask patterns at exact positions on the resist film. To this end, it is essential that the resist film onto which the images of the mask patterns are projected be exactly positioned at a focal point of the projection optical system of the exposure apparatus. The position of the resist film located is detected in such a manner that inspection light is applied to the resist film and the light reflected from the resist film is analyzed (for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-334826). When a plurality of metal wiring patterns are laid out under the resist film, the different reflectivities of the metal wiring patterns adversely affect the detection of the position of the resist film by the inspection light.